Counterbalancing device for window sashes



March 29, 1938. 1 T. GIRARD COUNTERBALANCING DEVICE FOR WINDOW SASHES Filed Aug. 51, 1936 L. S 42 FIG FIG NVENTOR LEO T. GIRARD A ZTORNEYS Patented Mar. 29, 1938 UNITED STATES PATENT OFFICE COUNTERBALANCING DEVICE FOR WIN- DOW SASHEVS 2 Claims.

This invention relates generally to counterbalancing devices and refers more particularly to improvements in window sash balancing mechanism of the spring actuated drum type.

One of the principal objects of this invention resides in the provision of sash balancing mechanism of the above type so `constructed that the weight of the sash is carried by the drum and associated parts rather than by the actuating spring. This is advantageous in that the degree of tension of the spring required for satisfactory operation is maintained over a long period of time, irrespective of theirequency of operation of the sash.

Another advantageous feature oi this invention consists in equipping the spring actuated drum with brake mechanism effective to resist movement of the sash to its closed position and ineiective to interfere with movement of the sash to its open position.

A further object of this invention consists in the provision of means responsive upon manipulation of a suitable adjustment to act directly on the spring actuated drum for resisting movement of the sash to its open position. This feature is advantageous in that it offers the possibility of employing a standard balancing unit for windows of various sizes and weights.

The foregoing, as well as other objects, will be made more apparent as this description proceeds, especially when considered in connection with the accompanying drawing, wherein:-

Figure 1 is a side elevational view of a balancing unit having the cover removed and constructed in accordance with this invention;

Figure 2 is a sectional view taken substantially on the plane indicated by the line 2-2 of Figure 1;

Figure 3 is a sectional view taken substantially on the plane indicated by the line 3-3 of Figure 2; and

Figure 4 is a side elevational view having certain parts broken away for the sake of clearness.

Referring now more in detail to the drawing, it will be noted that there is illustrated in Figures 1 to 4 inclusive, a sash balancing unit having a casing I comprising a section II and a removable cover l2 cooperating with the section Il to form a space of sufficient dimension to receive the balancing mechanism. It will be observed from Figure 1 that the casing thus formed is open at the inner end and that this opening is closed by means of a plate I3 permanently secured to the section IIJ. In actual practice, the casing I0 is housed in a recess formed in the window frame (not shown) adjacent the upper end thereof at one side of the sash and is lxedly secured to the inner surface of the side jamb of the frame by means of the ears I4 projecting from opposite ends of the plate I3.

of the drum is provided with an annular extension I9 extending axially outwardly from the marginal edges of the opening through the web and rotatably supported on the bearing I8. The opposite side of the drum I5 is supported on the bearing I8 by means of a disc 20 seated within an annular groove 2| formed in the inner surface of the annular flange I6 adjacent the free end of the latter and having an opening through the center of sufficient diameter to permit the disc to be journaled on the bearing I8. Both the extension I9 and disc 20 having a running fit with the bearing so as to permit free rotation of the drum relative to the bearing.

It has previously beenstated that the bearing I8 is of a sectional character, and it will be noted from Figure 2 that the two sections are respectively secured to opposite side wallsv of the casing I5 in axial alignment, by crimping the outer ends of the sections over the aforesaid side walls of the casing. In the present instance,

vthe cooperating sections of the bearing abut each other substantially vin a plane parallel to and midway between the opposite side walls of the casing I0. It will also be observed from Figure 2 that the two sections of the bearing I8 are axially bored to receive the fastener element 23 operable to clamp the two sections vof the bearing together and to secure the sections of the casing in assembled relationship.

In accordance with this invention, the sash is counterbalanced by means of a helical Spring 24 housed in the drum I5 with one end anchored to the drum ange I6, as .at 25, and with the opposite end anchored in registering slots 26 formed in the two sections of the bearing I8. The drum I5 is operatively connected to the sash 21 diagrammatically shown in Figure 3 in such a manner that when the sash is moved to its closed position, the drum I6 is rotated in the direction of the arrow 28'to tension the helical spring 24 and cause the latter to exert a force on the drum tending to rotate the latter in the opposite direction indicated by the arrow 29. The connection between the drum and the sash 21 comprises a tape 3U having one end wound around the exterior of the drum flange I6 and anchored to the ange in the manner designated by the reference character 3|. The other or free end of the tape is extended through a slot 32 in the plate I3 and is provided with a lug 33 for attachment to the sash 21.

' of the weight of the sash in any one of the open positions of the latter and this is accomplished in the following manner. Freely rotatably supported in the casing I0 on the bearing I8 adjacent the drum I6 is a brake drum 35 having'an annular brake flange 36 extending in the same direction as the drum flange I6 and having a series of circumferentially spaced serrations 31 on the inner annular surface of the brake flange. The outer surface of the brake flange is adapted to be engaged by a brake band 38 comprising a flexible steel ribbon having one end return-bent, as at 39, and secured to the casing, as at 40. The opposite end of the band is adjustably secured to the plate I3 by means of the screw 4I having an enlarged head accessible for manipulation at the front side of the plate I3 and having a shank threadedly engaging a nut 42 secured to the free end of the band. The arrangement is such as to resist rotation of the brake drum 35 with a pressure variable in dependence upon manipulation of the adjusting screw 4I.

The brake drum 35 is operatively connected to the drum I5 through the medium of one-way clutch mechanism comprising a pair of dogs 43 pivotally connected at their inner ends to the web I1 of the drum .I5 on diametrically opposite sides of the axis of this drum. Upon reference to Figure 2, it will be noted that the relationship betweenthe two drums is such as to permit the outer ends of the dogs to engage the serrations 31 formed on the inner annular surface of the brake flange 36, and the dogs are yieldably urged into clutching engagement with the brake drum by means of suitable leaf springs 44 carried by the web I1 of the drum I5 with the free endsengaging the dogs tending to urge the same against the stops 45, wherein the free ends of the same engage the serrations 31.

Upon reference to Figure 4, it will be noted that the outer ends of the dogs 43 are shaped to slide over the serrations 31 when the spring actuated drum I5 is rotated in the direction of the arrow 29 to open the sash. In other words, the brake mechanism is disconnected from the spring actuated drum I5 during the interval the sash is moved to its open position. However, it will also be noted that the contour of the outer ends of the dogs is such that when the spring actuated drum I5 tends to rotate in the opposite direction indicated by the arrow 28, the free ends of the dogs positively engage the serrations 31 on the inner surface of the brake ange 36 and thereby connect the brake mechanism to the `drum I5. With this arrangement, it will be noted that the sash is effectively held in any one of its openI positions through the action of the brake band 38 on the flange 36 of the brake drum 35, and movement of the sash to its closed position requires corresponding movement of the brake drum 35 against the friction offered by the brake band 38. It will, of course, be understood from the above that this friction may be varied to suit existing conditions by merely manipulating the adjustment screw 4I.

In the event it is desired to standardize the construction of the sash balancing unit and to employ the same in association with sashes having widely varying weights, a second brake mechanism may be provided for resisting movement ofthe sash toits open position. In other words, if a sash balancing unit designed to satisfactorily operate in connection with the average Vsize sash is employed in combination with a sash of relatively light weight, it is possible that the strength of the spring 24 may actually be sufdcient to effect movement' of the sash toward its open position. This, of course, would be objectionable and is overcome in the present instance by subjecting the portion of the drum adjacent the tape 30 to the action of the brake band 46.

\ The brake band 46 is preferably in the form of a steel tape similar to the brake band 38, but so assembled that the corresponding ends of the bands are opposite each other. As will be observed from Figure 1, the return-bent end 41 of the band 46 is secured to the side of the casing III Opposite that side to which the end 40 of the band 38 is secured, and thefree end 48 of the band 46 is adjustably connected to the plate I3 by means of the adjusting screw 49 having a head portion exposed at the front side of the plate for engagement by a suitable tool, and having a shank portion threadedly engaging a nut 50 anchored to the free end 48 of the band 46. Thus, it will be seen that the friction exerted on the drum by the brake band 46 may be varied by adjusting the screw 49 and the extent of adjustment is preferably such that the band 46 may be rendered entirely inoperative when desired.

What I claim as my invention is:

1. In adevice of the class described, a casing having substantially parallel walls, a drum in said casing, a bearing member for said drum carried by said walls, said drum having a web apertured to receive said bearing member, a helical spring housed within said drum having one end fastened to the drum and having the other end fastened to said bearing member, means connecting said drum to said sash, a brake drum freely mounted on said bearing member and having an annular flange, an adjustable brake band carried by the casing and engaging the annular flange of said brake drum, and a one-way clutch mechanism connecting the brake drum to the drum aforesaid including a series of circumferentially spaced serrations on the inner surface of the annular flange of said brake drum, a pair of dogs having their inner ends pivotally connected to the web aforesaid upon diametrically opposite sides of the axis of rotation thereof and having their outer ends engaging said serrations, and leaf springs carried by said web and constantly urging the free ends ofl said dogs into clutching engagement with said serrations.

2. In a device of the class described, a casing having substantially parallel walls, a drum in said casing, a bearing member for said drum carried by said walls, said drum having a web apertured to receive said bearing member, a helical spring .housed within said drum having one end fastened to the drum and having the other end fastened to said bearing member, means connecting said drum to said sash, a brake drum freely mounted on said bearing member and having an annular ange, an adjustable brake band carried by the casing and engaging the annular flange on said brake drum, and a one-Way clutch mechanism connecting the brake drum to the drum aforesaid including a series of circumferentially spaced serrations on the inner surface rof the annular flange. of said brake drum, substantially parallel leaf springs on said web, `and a pair of dogs located on said web between the Vparallel leaf springs and urged by the latter into clutching engagement with the serrations.

LEO T. GIRARD. 

